There have been known a technique of playing back subject images as a three-dimensional image by using a stereo vision of recognizing distance information between subjects by measuring parallax between two photographic images captured by a stereo camera.
In this conventional technique, there is however a possibility that visibility of the three-dimensional image may be lowered because the sizes of triangular polygons forming the three-dimensional image are affected by information of distances between points on the subjects. When, for example, the distance between subjects is large, the size of an image of a subject located near the camera is reduced extremely as shown in FIG. 22. In this manner, visibility of the three-dimensional image is lowered.
A publication JP-A-2005-167310 discloses a technique for changing a display image from a three-dimensional image to a two-dimensional image when the distance between subjects is too short or too long to display a three-dimensional image, that is, when the captured image is unsuited to three-dimensional expression. According to the technique described in the publication, the captured image can be always displayed in an optimum form.
In the technique described in the publication, JP-A-2005-167310, there is however a problem that a user cannot three-dimensionally confirm the state of a subject image when a captured image is unsuited to three-dimensional expression so that an image to be displayed is changed to a two-dimensional image completely.